August, 1944 



Ross: Caddis Flies of Illinois 



69 



gin; internal structures forming a pair of 

 wide, lateral lobes and a single mesal lobe. 



Allotype, female. — Spring Grove, Illi- 

 nois: May 22, 1938, Ross & Mohr. 



In Illinois this species has been taken 

 principally in the vicinity of the glacial lakes 

 in the northeastern part of the state (see 

 p. 10). It was recorded from Diamond 

 Lake, Illinois, May 30, as Holocentropus 

 species 1 Betten (1934, p. 223). Apparently 

 only one generation of adults appears each 

 year as indicated by our collection records, 

 which run from May 9 to August 12. 



The range of the species is poorly known. 

 In addition to our Illinois records we have 

 only the following: Michigan (Nottawa) 

 and Wisconsin ( Mukwonagon) . 



Illinois Records. — Antioch : July 1, 

 1931, Prison, Betten & Ross, i S ; July 6, 

 1931, Prison et al., 5 <S ; July 6, 1932, Prison 

 et al., 9 $ ; July 7, 1932, at light, Prison & 

 Metcalf, \S. Channel Lake: May 27, 

 1936, H. H. Ross, 1 $ pupa; June 11, 1936, 

 Ross & Burks, i$. Pox Lake: July 1, 

 1931, Prison, Betten & Ross, $ $ ; June 

 30, 1935, DeLong & Ross, 3 5 ; May 28, 

 1936, in weeds, H. H. Ross, $ $ , ?> larvae; 

 May 13, 1938, 1 9 . Havana: May 9, 1896, 

 Butler, 1 $. Spring Grove: Aug. 12, 1937, 

 at light, Ross k Burks, 2 $ ; May 20, 1938, 

 Ross & Burks, 1 $ ; May 22, 1938, Ross & 

 Burks, U , 19; May 23, 1938, Ross & 

 Burks, 3 $ ; June 4, 1938, Mohr & Burks, 

 1 $ ; May 31, 1 ^ ; June 10, 1 $ (reared). 

 Ottawa: June 3, 1938, Mohr & Burks, 



Polycentropus interruptus (Banks) 



Holocentropus interruptus Banks (1914, p. 

 257); c?. 



Holocentropus orotus Banks (1914, p. 257); 

 cf, 9. 



Holocentropus longus Banks (1914, p. 258); 



Larva. — Pig. 233. Length 15 mm. Head 

 yellowish with distinct dark spots and with 

 most of the dorsum clouded with reddish 

 brown, the major pair of setae of the upper 

 frons with a small, pale area around base. 

 Pronotum and legs yellowish brown. Re- 

 mainder of body pale. 



Adults. — Length 9-10 mm. Color vari- 

 ous shades of brown, the wings marked with 

 pale areas making a somewhat checkerboard 

 pattern. Pront wings with R., present, hind 

 wings with Rg absent. Male genitalia, fig. 



236: tenth tergite with a pair of long, 

 curved processes which are sclerotized, slen- 

 der and curved to follow the outline of the 

 aedeagus; cerci with the basal portion long 

 and widened at apex, bearing a short, sau- 

 sage-shaped apical projection; claspers 

 broad at base, tapering to a sharp, up- 

 curved point, and with only small flaps on 

 the mesal base. Pemale genitalia, fig. 251: 

 eighth sternite long and rounded at apex, 

 lateral lobes long and spatulate, with a 

 footlike angular base ; between these lobes 

 there is a deep depression in the tergite; 

 ninth sternite with a pair of long, sclero- 

 tized rods. 



In Illinois we have taken this species 

 recently only in lakes and ponds in the 

 extreme northeastern corner of the state. 

 The larvae were taken in weed beds and be- 

 neath stones in these situations and locally 

 were very abundant. Our adult records 

 indicate only one generation per year, all 

 falling between May 26 and July 15. Nu- 

 merous mature pupae from Channel Lake, 

 Pox Lake and Dead River (see p. 12) have 

 established the association of the larvae and 

 adults. 



The range of the species is extensive, in- 

 cluding Colorado, Illinois, Massachusetts, 

 Michigan, New Hampshire and New York. 

 These records, however, are based on a 

 minimum of definite localities, so that the 

 species appears to be very local in its occur- 

 rence. 



Illinois Records. — Many males, females 

 and pupae, taken May 26 to July 15, and 

 many larvae, taken May 27-28, are from 

 Algonquin, Antioch, Channel Lake, Pox 

 Lake, Grass Lake, Pistakee Lake, Rich- 

 mond, Spring Grove, Urbana, Volo, Zion. 



Nyctiophylax Brauer 



Nyctiophylax Brauer (1865, p. 419). Geno- 

 type, monobasic: Nyctiophylax sinensis Brauer. 



Only two Nearctic species are known for 

 this genus, one of them from Illinois, the 

 other from the Northeast. The larva has 

 not been associated with the adult, although 

 one species is very common and widespread 

 (see Genus A and Genus B, pp. 73 and 74). 



KEY TO SPECIES 



Adults 



1. Apex of abdomen with cerci and 



claspers, figs. 262, 263 (males).... 2 



